Process for preparing quick drying, plasticized sulfur road compositions

ABSTRACT

Process for preparing sulfur marking compositions comprising from about 50 percent to about 95 percent elemental sulfur, from about 1 percent to about 20 percent sulfur containing plasticizer and from about 0 percent to about 30 percent filler, comprising reacting said ingredients in the presence of a basic catalyst, the improvement which comprises incorporating in said reaction mixture a minor amount of a nitrogen containing compound as drying agent selected from mercaptobenzothiazoles, mercaptoalkylthiazoles, dithiocarbamates, bis(thiocarbamoyl) sulfides, guanidines and aldehyde-amine reaction products.

United States Patent [72] Inventor Lawrence A. Smalheiser Spring Valley,N.Y. [21] Appl. No. 781,580 [22] Filed Dec. 5, 1968 [45] Patented Oct.26, 1971 [73] Assignee Staufter Chemical Company New York, N.Y.

[54] PROCESS FOR PREPARING QUICK DRYING,

PLASTICIZED SULFUR ROAD COMPOSITIONS 12 Claims, No Drawings [52] US. Cl106/19, 94/1.5,106/286,106/287 [51] Int. Cl ..C09d 11/00, C09 d 13/00[50] Field of Search 106/19, 286, 287 S; 94/15; 23/114, 115, 138;260/607-609 [56] References Cited UNITED STATES PATENTS 2,799,593 7/1957Seymour et al. 106/287 S 3,020,252 2/1962 Hancock 106/19 X Primary ExaminerJulius Frome Assistant Examiner-Joan B. Evans Attorneys-Donald M.Mackay, Robert C. Sullivan, Paul J.

Juettner and Daniel C. Block ABSTRACT: Process for preparing sulfurmarking compositions comprising from about 50 percent to about 95percent elemental sulfur, from about 1 percent to about 20 percentsulfur containing plasticizer and from about 0 percent to about 30percent filler, comprising reacting said ingredients in the presence ofa basic catalyst, the improvement which comprises incorporating in saidreaction mixture a minor amount of a nitrogen containing compound asdrying agent selected from mercaptobenzothiazoles,mercaptoalkylthiazoles, dithiocarbamates, bis(thiocarbamoyl) sulfides,guanidines and aldehyde-amine reaction products.

PROCESS FOR PREPARING QUICK DRYING, PLASTICIZED SULFUR ROAD COMPOSITIONSThis invention relates to road-marking compositions comprising sulfurand a sulfur-containing plasticizer, which have improved dryingcharacteristics, and to a process for preparing these novelcompositions.

Although a variety of paints have heretofore been used for markingroads, parking lots, airport runways, and the like, the limiteddurability of these paints has initiated considerable research for othersurface coating compositions. For example,

compositions containing a major amount of sulfur have been recentlyproposed for use in various marking applications by reason of their lowcost, resistance to water, oils and the like, and also for such reasonsas their increased impact resistance. Generally, these compositionscontain from about 50 to about 95 parts elemental sulfur by weight ofthe composition excluding fillers, pigments, viscosity reducingcompounds, plasticizers, and the like. One of the difficultiesencountered with many sulfur road-marking compositions, however, is thatthe compositions require approximately minutes or more to dry afterbeing applied to the road surface. While these drying times are lessthan those required for the commonly employed paints, the provision of aquick-drying composition would obviate the need for markers and theaccompanying labor cost required for laying the markers to protect thestripes from traffic until the stripes are dry and also the labor costof removing the markers. Accordingly, an inexpensive fast-drying sulfurcomposition would be more able to compete with the less inexpensivepaints which, for the most part, now have the bulk of the market.

It has now been discovered that quick-drying plasticized sulfurcompositions can be prepared by incorporating with the plasticizer andelemental sulfur a minor amount of a nitrogencontaining compound asdrying agent. Exemplary of nitrogencontaining compounds which serve asdrying agents are mercaptobenzothiazoles, mercaptoalkylthiazoles,dithiocarbamates, bis (thiocarbamoyl) sulfides, guanidines,andaldehydeamine reaction products such as hexamethylene tetraamine. Themercaptobenzothiazoles can be represented by;

/ n LCH C-I? v Y z n CHzC-N wherein Y, n and n are as previouslydefined. Examples of suitable mercaptoalkylthiazoles include thefollowing compounds wherein CH3CN CHaO-III The dithiocarbamates cab beEEQaQiiadiJ the formula:

mate, selenium diethyldithiocarbamate, lead dimethyldithiocarbamate,selenium dimethyldithiocarbamate, tellurium diethyldithiocarbamate, andzinc pentamethylenedithiocarbamate.

The bis(thiocarbamoyl sulfides also known as thiuram sulfides, can berepresented by the formula:

mils. (Y2 /2- wherein the groups represented by Yare alkyl of from oneto four carbon atoms inclusive or are taken together to form a saturatedring, and n is as previously defined. Examples of suitablebis(thiocarbamoyl) sulfides include: bis(dimethylthiocarbamoyl)disulfide, bis(dimethylthiocarbamoyl)sulfide,bis(diethylthiocarbamoyl)disulfide,bis(di-nbutylthiocarbamoyl)disulfide, andbis(dibutylthiocarbamoyl)sulfide.

The guanidines which can be employed-are: l,3-diphenylguanidine, andl,3-di-o-tolylguanidine.

The aldehyde-amine reaction products which can be employed are theproducts prepared from reacting aldehydes of from oneto seven carbonatoms with secondary amines of from one to ten carbon atoms or ammonia.Examples of suitable aldehyde-amine reaction products include thereaction products of: butyraldehyde and butylideneaniline; butyraldehydeacetaldehyde and aniline; formaldehyde and paratoluidine;butyraldehydeand aniline; butyraldehyde and butylamine; ammonia andacetaldehyde; heptaldehyde and aniline; formaldehyde and ammonia, andethyl chloride, formaldehyde and ammonia.

The preferred drying agents are the metal dithiocarbamates asexemplified by zinc diethyl dithiocarbamate, and zincdimethyldithiocarbamate; the bis(thiocarbamoyl) sulfides as exemplifiedby bis(dimethylthiocarbamoyl) sulfide and bis(dimethylthiocarbamoyl)disulfide; and the mercaptobenzothiazoles as exemplified by2-mercaptobenzothiazole. With the preferred drying agents, generallysuperior results are produced and these drying agents are more readilyavailable.

The compositions of this inverition comprise essentially a major amountof elemental sulfur, a minor amount of sulfurcontaining plasticizer anda minor amount of nitrogen-containing compound as drying agent.

Among the plasticizers which can be employed in this invention are thepolysulfide plasticizers wherein the bridging links between adjacentsulfur atoms in the polymer chain include an aromatic radical and/or analiphatic radical to include aliphatic either linkages. Typical of theseplasticizers are styrene polysulfide which has the repeating unit-C;H;,C H,S and is available as Thiokol polymer ZM-399. Anotherpolysulfide plasticizer in this group is one having the repeating unit-CH,-C H -CH -S,wherein x is an integer of from 2 to 16.

The aliphatic polysulfides containing either linkages are exemplified byThiokol LP3 which has the recurring unit S,CH ChOCH OCI-I CH S,wherein xhas a value of 43nd the polymer has a molecular weight of about 1,000.U.S. Pat. No. 2,402,977, issued July 2, 1946 to Patrick et a]. describesin detail the manner of forming the organic polysulfide polymers ofinterest to the present invention and the ingredients involved in theformation thereof.

Other plasticizers which can be utilized in this invention are thedimercaptans of the general formula HS-(A),,-SH wherein A is selectedfrom the group consisting of two to carbon alkylene and chalcogeninterrupted alkylene having from two to 10 carbon atoms, and n is aninteger of from 1 to 2. Exemplary of suitable chalcogens are oxygen andsulfur. Illustrative of suitable plasticizers encompassed by the aboveformula are BB -dimercaptodiethyl ether, triethylene glycol dimercaptan,1,6-hexane dimercaptan, l,l0-decane dimercaptan, 1,3- propanedimercaptan, ethylene glycol bis(thioglycolate), and ethylene glycolbis(mercaptopropionate).

Other suitable plasticizers which can be employed are represented by theformula R-S-R wherein the groups represented by R are secondary amines.Examples of suitable secondary amines for the purposes of this inventioninclude: aliphatic amines such as dimethylamine, ethyl methylamine,diethylamine, diisopropylamine, dibutylamine, dipentylamine, anddidodecylamine; alicyclic amines such as dicyclohexylamine anddicyclopropylamine; aromatic amines such as diphenylamine,N-phenyl-l-naphthylamine, N-phenyl-2 naphthylamine, N-methylphenylamine,N-ethylphenylamine; and heterocyclic amines such as ethyleneamine,hexamethyleneamine, morpholine, piperidine, tetrahydroquinoline,tetrahydropyrrole, 1,2,3-dioxazole, p-isoxazine, and indole.

These plasticizers are prepared by reacting the desired amine with asulfur halide in a molar ratio of at least 2:1. An inert organic solventis employed and the reaction is conducted in the presence of an alkalinematerial, such as sodium carbonate, at a temperature below about 30 C.

Other suitable plasticizers are prepared by reacting a polymercaptanwith a compound containing an episulfide group. The polymercaptans whichcan be utilized are represented by the formula:

HS-R-(SH), Wherein R is a hydrocarbon containing up to and includingcarbon atoms per molecule and n is an integer of from 1 to 2 inclusive.Illustrative of the hydrocarbon radicals as represented by R above arecyclic and acyclic aliphatic, aryl, and alkaryl. Representative exampleof suitable polymercaptans that can be employed include cyclo-aliphaticcompounds, such as dimercaptocyclohexane, dimercaptocyclopentane,dimercaptomethylcyclohexane, dimercaptoethylcyclohexane,dimercaptoalphaterpinene, dipentene dimercaptan, dimercaptodicyclopentadiene, dimercaptodi(methylcyclopentane),trimercaptocyclododecane, and dimercaptocyclooctane. Representativeexamples of suitable acyclic aliphatic polymercaptans includedimercaptoethane, dimercaptopropane, dimercaptobutane,dimercaptodiethylether, dimercaptotriethyleneglycol, dimercaptohexane,dimercaptodecane, ethyleneglycol bis (thioglycolate), and ethyleneglycolbis (mercapto propionate). Representative examples of suitable arylpolymercaptans include dimercaptobenzene, dimercaptonaphthalene andanthracenedimercaptan. Representative examples of suitable alkarylpolymercaptans include dimercaptomethylbenzene dimercaptoethylbenzene,dimercaptostyrene, dimercapto isopropylbenzene, dimercaptoxylene,dimercaptotoluene and p-dimercapto diethylbenzene. Preferredpolymercaptans are those having a mercapto ethyl or propyl substituent,such as dimercaptoethylcyclohexane, dimercaptoisopropyl cyclohexane,dipentendimercaptan, dimercaptoethylbenzene, dimercaptoisopropylbenzene,dimercaptoethyltoluene and the like.

Representative examples of suitable compounds containing an episulfidegroup include ethylene sulfide, propylene sulfide, l-butene sulfide andcyclohexene sulfide. These plasticizers are prepared by reacting thepolymercaptan with 'the episulfide in a molar ratio of at least about 1mole of episulfide per mole of mercapto group in the polymercaptan inthe presence of an acidic catalyst such as boron trifluoride. Thereaction is conducted for between about 10 and about 20 hours at atemperature between about 0 C. and C. Other plasticizers which can beemployed are represented by the general formula:

[(CHz)x'-( ;OCR R -(CH:) -iCR ROg-(CHz)x'S;]n wherein x is an integer offrom I to 3 inclusive, R R", R, R are one to three carbon alkyl orhydrogen, y is an integer of from 1 to 5 inclusive, z is an integer offrom 2 to 6 inclusive, and n is an integer of from about 2 to about 100.

These plasticizers are prepared by the interfacial polycondensation of adihalo-substituted diacylated glycol with an aqueous sodium polysulfidesolution. A freshly precipitated magnesium hydroxide dispersion is usedas a nucleating agent, and if desired, a dispersing agent of thealkyl-aryl sulfonate type. The polysulfide is then recovered from thedispersion by acidification to a pH between 4 and 5 which causes thedispersion to coagulate as a rubbery material.

Some representative examples of dihalides which may be utilized in thereaction include the following: ethylene bis (chloroacetate, ethylenebis(3-chloropropionate), ethylene bis(4-chlorobutyrate), l,2-propanebis(chloroacetate), 1,3- propane bis(chloroacetate), and2-methyl-2,4-pentane bis (chloroactate).

Examples of suitable polysulfides for reaction with the dihalideinclude: sodium disulfide, sodium trisulfide, sodium tetrasulfide andsodium pentasulfide.

Examples of suitable plasticizers within the formula include: ethylenediacetate tetrasulfide, 1,2-propane diacetate tetrasulfide, and2methyl-2,4-pentane diacetate disulfide.

Other suitable plasticizers include: dialkenyl polysulfide plasticizerswhich are prepared by the condensation of an alkenyl halide with anaqueous sodium polysulfide solution in a molar ratio of alkenyl halideto polysulfide of 2:1. Representative examples include: diallyltetrasulfide and diallyl disulfide.

Other additives such as viscosity reducing compounds can also beemployed. Illustrative of the viscosity reducing compounds are thosecompounds having a single reactive site to include:

a. monomercaptans of the formula:

RSH wherein R is selected from halogen substituted and unsubstitutedaryl and alkyl and hydroxyalkyl of from two 20 carbon atoms inclusive;

b. monobasic acid monomercaptans of the formula:

wherein n is in integer of from 1 to 3 inclusive, and R is selected fromhydrogen, sodium, potassium, ammonium, and alkyl, and hydroxyalkyl offrom one to 20 carbon atoms inclusive;

c. polysulfides of the unit:

LR Sn J wherein R" is selected from phenyl and aralkyl and alkyl of fromtwo to carbon atoms inclusive, and n is an integer greater than 1, and

d. styrene.

Representative examples of viscosity reducing chain terminatingcompounds include: thiol acids such as thiobenzoic acid, thioaceticacid, thiolauric acid and thiopalmitic acid; alkyl mercapto-alcoholssuch as mercaptoethanol, mercaptopropanol, mercaptobutanol,mercaptopentanol, mercaptohexanol, mercaptoheptanol, mercapto-octanol,mercap todecanol, mercaptododecanol and mercaptohexadecanol; alkarylmercaptans such as thiocresol; substituted aryl mercaptans such asparachlorothiophenol; monobasic acid monomercaptans and their alkalimetal and ammonium salts such as mercaptoacetic acid, mercaptopropionicacid, ammonium thioglycolate, potassium thioglycolate and sodiumthioglycolate; monobasic acid ester monomercaptans such as t-butylmercaptoacetate iso-octyl mercaptoacetate, iso-octyl mercaptopropionateand octadecyl mercaptopropionate; hydroxya'lkyl esters of monobasic acidmonomercaptans such as hydroxyethyl mercaptoacetate and hydroxyethylmercaptopropionate; alkyl polysulfides such as diethyl trisulfide,diethyl disulfide, dipropyltetrasulfide, dihexyl disulfide and didecyldisulfide; aromatic polysulfides such as diphenyl disulfide; aralkylpolysulfides such as dibenzyl disulfide, dibenzyl trisulfide anddibenzyl tetrasulfide; and olefinically unsaturated compounds such asstyrene. I H

Preferred however, are the aliphatic monomercaptan monobasic acidesters, such as iso-octyl mercaptoacetate, the aliphaticmercapto;alcohols, such as mercaptoethanol, the alkaryl mercaptans suchas thiocresol, and the chlorosubstituted aryl mercaptans such asparachlorothiophenol. These preferred viscosity reducing compounds areeffective at much lower concentrations than some of the other compoundssuch as the alkyl mercaptans. If used, generally a minor amount of fromabout 0.05% percent to about 10 percent of viscosity reducing compoundis sufficient, and preferably from about 0.2 percent to about 5 percentis used.

Generally, a minor amount of drying agent will be sufficient such asfrom about 0.05 percent to about 10 percent and preferably from about0.1 percent to about 2 percent. The plasticizer can be present in anamount from about 1 percent to about 20 percent but generally from about5 percent to about 10 percent will be sufficient. The quantity ofelemental sulfur should be at least about 50 percent, however, theamount of elemental sulfur may be as great as 95 percent by weight ofthe total composition, and yet the composition is quick drying. Thefiller, if present, can constitute up to about 30 percent of thecomposition.

The compositions can be prepared by dry-mixing the ingredients prior toheating or by adding the tiller, additives, drying agent and plasticizerto the molten sulfur. For best results, however, in order to avoid thedecomposition of the drying agent and other additives, the followingorder of addition is employed. First, the plasticizer is added to themolten sulfur while the sulfur is maintained at a temperature betweenabout 1 18 C. and about 149 C. The mixture is then heated to atemperature between about 163 C. and about 188 C. and maintained at thistemperature for at least about 15 minutes.

The reaction mixture is then allowed to cool to a temperature of aboutC. wherein the pigments and other fillers are added which causes thetemperature of the reaction mixture to recede to about l2l C. The dryingagent is then added to the reaction mixture at this temperature and thecompositions are ready for use as road marking compositions.

The compositions can be applied to any paved surface by conventionalmeans such as, for example, by an applicator of the type used forapplying paint which has been adapted to permit maintaining thetemperature of the composition at about C.

The following examples will serve to illustrate the invention and itspreferred embodiments. All parts and percentages in said examples are ona weight basis.

EXAMPLE l in a 4-liter metal container, the following materials aredrymixed: 72.9 parts elemental sulfur, 6.0 parts [3,B'-dimercaptodiethyl ether plasticizer, 20 parts titanium dioxidepigment, 200 parts per million toner, 0.6 parts Z-mercapto-ethanolviscosity reducer, 0.5 parts hydrated silica and 0.5 partsbis(dimethylthiocarbamoyl) monosulfide drying agent. The mixture isheated for 2 hours at l50 C. and then heated for 1 hour at 175 C. Themixture is then sprayed while at a temperature of C. to a paved surfacewith a flat spray tip having a 0.072 inch orifice diameter and sprayangle at 40 p.s.i. of 65. The strip which is 2-92 inches wide and has athickness of 54 mils dries in approximately l-9 minutes.

EXAMPLE 2 In accordance with the procedure of example 1, an identicalcomposition is prepared with the exception that thebis(dimethylthiocarbamoyl) monosulfide drying agent is omitted. Thecomposition when sprayed on a road surface requires 6 minutes to dry.

EXAMPLE 3 In accordance with the procedure of example 1, a compositionis prepared and sprayed which differs from the composition of example 1in that 0.5 parts of zinc dimethyldithiocarbamate is substituted for thedrying agent of example 1. The composition, when sprayed on a pavedsurface with a width of 3-95 inches and a thickness of 30 mils, dries inthree-quarters of 1 minute.

EXAMPLE 4 In accordance with the procedure of example 1, a compositionis prepared and sprayed which differs only in that the drying agent isthe zinc salt of Z-mercaptobenzothiazole. The composition when sprayedas a 3-inch wide strip with a thickness of 28 mils is found to dry inthree-quarters of 1 minute.

EXAMPLE 5 In accordance with the procedure of example 1, a compositionis prepared and sprayed having the following ingredients: 69.4 partssulfur, 10 parts triethylene glycol tetrasulfide plasticizer, 20 partstitanium dioxide, 350 parts per million toner, 0.6 parts2-mercaptoethanol viscosity reducer, and 0.5 parts zincdimethyldithiocarbamate drying agent. The composition, when sprayed as afour inch wide strip with a thickness of 23 mils, dried inthree-quarters of 1 minute.

EXAMPLE 6 in accordance with the procedure of example 1, sixcompositions are prepared each employing one of the following dryingagents: 2,2-dithiobis (4,5-dimethylbenzothiazole), 1,3-diphenylguanidine, zinc diethyldithiocarbamate, bis(dimethylthiocarbamoyl) disulfide, zinc salt of 2-mercaptobenzothiazole,and the reaction product of butyraldehyde, acetaldehyde and aniline.When applied as stripes to a road surface, the drying times correspondto the previous examples.

Although the drying time is dependent upon the percentage of pigment inthe composition, the plasticizer employed and the drying agent employed,the compositions of the invention will have considerably shorter dryingtimes than similar compositions having no drying agent.

What is claimed is:

I. In a process for preparing sulfur marking compositions comprisingfrom about percent to about 95 percent elemental sulfur, from about 1percent to about percent sulfur containing plasticizer and from about 0percent to about 30 percent filler, comprising reacting saidingredients, the improvement which comprises incorporating in saidreaction mixture a minor amount of a nitrogen containing compound as adrying agent selected from the group consisting ofmercaptobenzothiazoles, mercaptoalkylthiazoles, dithiocarbamates,bis(thiocarbamoyl)sulfides, and guanidines.

2. The process of claim 1, wherein the drying agent is amercaptobenzothiazole of the formula s [I o s Y.

3. The process of claim 1, wherein the drying agent is a dithiocarbamateof the formula wherein the groups represented by Y are alkyl of from 1to 4 carbon atoms inclusive, benzyl or are taken together to form asaturated ring; M is a heavy metal and n is an integer of from 1 to 2inclusive.

4. The process of claim 1, wherein the drying agent is abis(thiocarbamoyl) sulfide of the formula wherein the groups representedby Y are alkyl of from one to four carbon atoms inclusive or are takentogether to form a saturated ring, and n is an integer of from 1 to 2inclusive.

5. The process of claim 1 wherein the drying agent isbis(dimethylthiocarbamoyl) m'onosulfide.

6. The process of claim 1, wherein the drying agent is zincdimethyldithiocarbamate.

7. The process of claim 1 wherein the drying agent is2-mercaptobenzothiazole.

8. The process of claim 1 wherein the drying agent is 2,2

dithiobis (4,S-dimethylbenzothiazole).

9. The process of claim 1 wherein the drying agent is 1,3-diphenylguanidine.

10. The process of claim 1 wherein the drying agent is zincdiethyldithiocarbamate.

11. The process of claim 1 wherein the drying agent isbis(dimethylthiocarbamoyl) disulfide.

12. The process of claim 1 wherein the drying agent is zinc salt ofZ-mercaptobenzothiazole.

Patent No.

UNHTU STATES PATIQIJT OFFICE CEREHEECATE GE CGRIFLECTIQN October 26,1971 5,615,748 Dated Lawrence A. Smalheiser It is certified that errorappears in the above-identified patent and that said Letters Patent arehereby corrected as shown below:

Column 1, line &0, delete the semicolon after the word "by and ColumnColumn Column insert -the formul'a;- line 55, delete the word"including" and in its place insert the word --include--; line 54,delete "S.C. H SCH NH) CO; and in its place insert --(S.C H .N:C.SCH NH)C0;-- line'55 and 56 delete "(8. C n N:C. SC H (N0 and in its placeinsert C H .N: SC HC(N0; line 58, delete ($.c. H )N: C. S-CSN can 7 and'in its place insert C H .N: S- CSN(C H line 60, delete"linothiobenzethiazole)" and in its place insert--linothiobenzothiazole)- line 60, delete "(s. c. H N:C. SN. c2H 0. c 21and in its .C H O. 2H4) line 61 place insert C H N: L1 51 delete "(5. CH .N:C. 5 and in its place insert 1 --(S.C H .N:C) S lines'62, 65 and 6delete all words after the word 'benzothiazolesulfenamide" and add C H.N:. SNHC H 1 N,N-diisopropylbenzothiazole-2- sulfenamide; andN-tert-butyl-2-benzothiazolesulfenamide. line 52, after the word"bis(thiocarbamoyl" insert line 28, delete the word "either" and insertthe word -ether--; line 29, after the word "unit" delete the hyphen;line 50, delete "-S CH ChOCH 0CH CH S and insert -S CH CH OCH line55,after the word "(chloroacetate" insert a parenthesis. line 1, delete thewords "two 20" and insert in its place -2 to 20-- line +5, after theword "mercapto" delete the semicolor and in its place insert a hyphen;line 52, delete "0. 05% percent" and in its place insert -.05%-- line55, delete "0.05 percent" and in its place insert .05%- Example 1, line27, delete "0.072" and in its place insert line 45, after the first "F"insert a comma. 5

UNITED SKATES PATENT OFFICE CEllilFlCii 0E5 CGRRECTIGN Patent No. 56l5,748 Dated October 26 1971 I fl Larence A. Smalheiser PAGE 2 It iscertified that error appears in the aboveidentified patent and that saidLetters Patent are hereby corrected as shown below:

Column 8, Claim 3, line 2, after the word "formula" insert the folowingformula S Y n N-C-S M Y n Column 8, Claim line 7, after the word"formula" insert the following formula Signed and sealed this 25th dagof A il 1972.

(SEAL) Atte st EDWARD MFLETCI-IEH, JR. ROBERT GOTTSGHALK AttestingOfficer Commissioner of Patents

2. The process of claim 1, wherein the drying agent is amercaptobenzothiazole of the formula
 3. The process of claim 1, whereinthe drying agent is a dithiocarbamate of the formula wherein the groupsrepresented by Y1 are alkyl of from 1 to 4 carbon atoms inclusive,benzyl or are taken together to form a saturated ring; M is a heavymetal and n is an integer of from 1 to 2 inclusive.
 4. The process ofclaim 1, wherein the drying agent is a bis(thiocarbamoyl) sulfide of theformula wherein the groups represented by Y2 are alkyl of from one tofour carbon atoms inclusive or are taken together to form a saturatedring, and n is an integer of from 1 to 2 inclusive.
 5. The process ofclaim 1 wherein the drying agent is bis(dimethylthiocarbamoyl)monosulfide.
 6. The process of claim 1, wherein the drying agent is zincdimethyldithiocarbamate.
 7. The process of claim 1 wherein the dryingagent is 2-mercaptobenzothiazole.
 8. The process of claim 1 wherein thedrying agent is 2,2-dithiobis (4,5-dimethylbenzothiazole).
 9. Theprocess of claim 1 wherein the drying agent is 1,3-diphenylguanidine.10. The process of claim 1 wherein the drying agent is zincdiethyldithiocarbamate.
 11. The process of claim 1 wherein the dryingagent is bis(dimethylthiocarbamoyl) disulfide.
 12. The process of claim1 wherein the drying agent is zinc salt of 2-mercaptobenzothiazole.